A wireless network is a network of stations that wish to communicate with each other. Stations communicate on a radio frequency (RF) medium on channels. In particular, stations transmit and receive information on a serving channel. In addition to communicating with other stations on the serving channel, a station also needs to gather information regarding other channels in the network. The station gathers information regarding other channels in the network so that when the station needs to change channels (also called handoff) the station will have the necessary information for the handoff. Gathering information is done by a scanning process. In the scanning process, a first station leaves its serving channel and collects information about other channels in the wireless network. If a second station were to transmit data to the first station while the first station was scanning other channels, the data transmitted by the first station would be lost. Losing transmitted data is undesirable because the first station must retransmit the previously transmitted data. Having to retransmit previously transmitted data is called a retransmission penalty.
Techniques presently known to avoid the retransmission penalty include periodical scanning and power management driven scanning. Periodical scanning is performed when a station performs the scanning process according to a schedule, e.g. after a fixed time period. In other words, the time that the station will be on the serving channel and the time when the station will be away from the serving channel is periodical according to a schedule which is often predefined. In periodical scanning, the station needs to notify stations in its vicinity about its schedule so that the retransmission penalty is minimized. Power management driven scanning is performed when scanning is linked with a power save mechanism. In other words, the scanning process is performed during the time that a station is asleep, e.g., the station is not transmitting or receiving data for a predefined period of time. However power management driving scanning is suboptimal for periods of time where high amounts of data are transmitted, e.g. heavy loading periods. One reason is that during heavy loading periods the station has to stay awake for long periods of time which leads to delays in scanning. Another reason is that during heaving loading periods, the power management driven scanning process requires a power-save mechanism to be implemented at the station which adds complexity to the scanning process.
In light of the above discussion, there is a need for a new method for managing scanning of channels in a wireless network.
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